Harat, Centrosome tn Nerve Cell. 33 
cells of Petromyzon; by Ayers! (’96) in the motor cells of the 
electric lobes of Torpedo; by von KO6LLIKER’® (97) in adult 
human giant pyramidal cells; by HAmAKER’® (’98) in the ner- 
vous system Nereis virens, Sars; by Ho~mGrREn* (’gg) in the 
spinal ganglion cells of Lophius piscatorius; by NELIs° (’00) 
in the spinal ganglion cells of cat, dog, and pig under patho- 
logical conditions. 
We may adda few words concerning the position of the 
centrosome. As was mentioned already, von LENHOSSEK dis- 
covered the centrosome in the concentric protoplasmic area, 
which is visible in the spinal ganglion in which the nucleus lies 
eccentrically. These peculiar concentric areas lie on the side of 
the nucleus toward the axone hillock and at a distance from it. 
DEHLER has found the centrosome in the same locality as von 
LeENHOSSEK, although he has noticed a smaller number of cen- 
tral corpuscles than the former investigator. Recently BUHLER 
and Ho_mGREN have expressed a view opposed to that of von 
LENHOSSEK, maintaining that the concentric area of the spinal 
ganglion cells isa locality where the fibrillar structure of the 
protoplasm which is continuous with the axis cylinder runs from 
the axone hillock toward the nucleus forming an area in which 
there appears a somewhat concentric arrangement. They did 
not find the centrosome in that area but in the immediate neigh- 
borhood of the nucleus. According to these investigators, the 
centrosome as well as sphere of von LENHOSSEK are nothing 
1 Ayers, HowarD—The origin and growth of brain cells in the adult body. 
Jour. of Comp. Neurology, Vol. vi (96), No. 3. 
2 Von K6LLIKER, A.—Handbuch der Gewebelehre des Menschen. Bd. ii 
(97), Lespzzg, p. 812. 
3 HAMAKER, J. A.—The nervous system of Nereis virens, Sars. A study 
in comparative neurology. Bull. of the Mus. of Comp. Zool. at Harvard Coll., 
Vol. xxxii (’98), No. 6, pp. 89-124. 
4 Ho_MGREN, E.—Zur Kenntniss der Spinalganglienzellen von Lophius 
piscatorius. <Anatomische Hefte, Bd. xii, Heft 1, ’99. 
5 NeLis, C.—L’apparition des centrosome dans les cellules nerveuses au 
cours de l’'infection rabique. Le Mévraxe, 1900, Vol. 1, Fasc. 1, 
